Apparatus for pre-processing tow



July 5, 1966 J. B. STEVENS ETAL 3,258,823

APPARATUS FOR PRE-PROCESSING TOW 3 Sheets-Sheet 1 Filed Feb. 20. 1962 m ESE JOEL B. STEVE/VS A7' TOR/VE YS July 5, 1966 J. B. STEVENS ETAL 3,258,823

APPARATUS FOR PRE-PROCESSING TOW Filed Feb. 20, 1962 5 Sheets-Sheet 2 TOl HALE JOEL B. STEVENS ROBERT C YA/VTZ INVENTORS BY M Mwu ATTORNEYS July 5, 1966 J. B. STEVENS Em. 3,258,823

APPARATUS FOR PRE-PROCESSING TOW Filed Feb. 20, 1962 3 Sheets-Sheet 5 JOEL 5. STEVENS ROBERT C. YA/VTZ INVENTORS A T TOR/VE YS United States Patent 3,258,823 APPARATUS FOR PRE-PROCESSING TOW Joel B. Stevens and Robert C. Yantz, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Feb. 20, 1962, Ser. No. 174,517 4 Claims. (Cl. 28-1) This invention relates to process and apparatus for the pre-processing of tow. More particularly, this invention concerns process and apparatus for treating tow whereby the tow is rendered in an improved condition for manufacture into a rod-like structure or element for tobacco smoke filters or other products and uses.

As is known in the industry, at the present time a large number of these rod-like members, plugs or elements are made from continuous multitilament tow. Such tow is received at the factory of the plug manufacture usually in the form of a compacted package, such as a bale or container or other unit carrying the tow. That is, for efficiency of shipping and the like the filaments are usually substantially compacted. The laments are withdrawny from the compacted package or other supply Source. The Withdrawn filaments are then passed through various devices including pigtail guides, large rol1s,fjets and other means to open up the bundle of tow filaments -prior to forming ythe filaments into the rod-like form or other configuration for cigarette lter use as well as other uses.

Such procedures and apparatus means as just mentioned are extensively used, are ellicient and give good products. However, in some instances, as when the rod is to be used for a cigarette filter, it has been noted that the uniformity of the rod-like elements may not be of as high a standard as desired. In further detail, rods of a weight in grams in excess of approximately .82 have in some instances been more uniform than somewhat comparable rods of a weight below .8. As apparent, it is economically desirable to manufacture rods of as light a weight as possible consistent with quality. Although as just indicated, rods of somewhat increased weight in some instances seemingly have possessed better uniformity still further increasing the rod weight does not better the uniformity but on the other hand adds to the cost and may unduly increase the pressure drop of the rod.

Therefore, it is thought apparent that the development of process and apparatus whereby such rod-like elements may be produced with enhanced uniformity and may be manufactured at a relatively light weight represents a highly desirable result. After extended investigation, we have arrived at procedure which permits increased uniformity of the articles of the class indicated and which procedure we believe is new and unobvious although relatively simple and economical as will be apparent from the detailed description hereinafter set forth.

This invention has for one object to provide process and apparatus for pre-processing, as illustrated by pretensioning of tow. A particular object is to provide process and apparatus as aforementioned which enhances the tow in a manner whereby the tow makes up into a more uniform cigarette filter. Still another object is to provide process an-d apparatus of the type referred to which is relatively simple, economical and lends itself to incorporation into currently used setups for manufacturing rod-like plugs and elements. Still another object is to provide an improved rod-like element wherein any deviation from element to element is relatively negligible and of a low standard deviation value. Still another 3,258,823 Patented July 5, 1966 ICS object is to provide a novel roll arrangement which may be interconnected and correlated with other parts for accomplishing the foregoing objects. Other objects will appear hereinafter.

In the broader aspects of our invention we have found that if the tow as it is removed from the shipping package Vis subjected at an early stage in the processing of the tow to a treatment we term pre-tensioning that observably better results and product may be obtained.

This pre-tensioning of the present invention preferably is applied by apparatus means that produces a constant tension on the tow and is sensitive to changes in length and weight of tow delivered to the further apparatus parts making up subsequent steps of the process. We have found that this can be accomplished in several Ways. This can be accomplished by a tension gate consisting of two rows of rods, one stationary and one movable, between which the tow passes at an angle of approximately to the axes of 4the rods. The movable rods are spaced as to fit in between the stationary rods and are weighted so that the tension is applied by the tow being pulled over the surface of the rods.

While a tension gate means as just mentioned may be used and have been referred to for illustrating the broader scope of the present invention, we prefer preatensioning by means of an arrangement of two relatively small rolls as will be described in detail hereinafter and will comprise the principal further description of apparatus means. That is, we have found lthat the pre-tension which we have discovered and which is particularly useful in operations of the class under discussion, may be applied by pulling the tow through the bite of two rubber covered rolls, or one rubber covered and one steel roll,A to which a brake has been applied preferably to one roll. Incidentally and as will be noted from the further description, this small'roll embodiment which is particularly preferred, in size and appearance resembles to some extent the structures associated with the now regarded as old-fashion wringer rolls on domestic washing machines used in the past.

However, as will be further noted from the description, the operation and braking of our small pre-tensioning rolls is interconnected and correlated with certain other apparatus parts utilized later in the process and which are in series with the pre-processing procedures of the present invention. The brake may be of any number of known braking procedures such as a weighted shoe on a drum, an electromagnetic brake, a hydraulic dynamometer or a spring or weight loading one roll against the other.

We have discovered that in the instant process wherein our so-called pre-tensioning is applied relatively early in the process, as approximately immediately after the tow is removed from the package, that better operation and results such as a more uniform product may be obtained. The present procedure is thought to be some what in contrast to prior procedures wherein greater emphasis on the tow treatment has been at later stages of manufacture more closely associated with the steps just before the tow is subjected to the rod-forming operations.

.The present invention, therefore, may be considered as having some similarity to U.S. Patent 2,908,045a patent of one of the herein named inventors. However, there is no conflict with this patent inasmuch as the several features of the present invention may be used apart or in conjunction with the means described in said patent.

As discussed above, although there are several types of apparatus constructions which will produce a pre-tensioning effect such as desired in the present process for securing better uniformity of product, we prefer to use a system of small rolls which are correlated and interconnected in a certain manner with a jet device positioned later on in the process and in series with the pre-processlng.

For assistance in a further understanding of this invention, reference is made to the attached drawings forming a part of this application. -In the drawings, FIGURE 1 is a diagrammatic representation somewhat in the nature of a ow sheet of the overall method in accordance with this invention.

FIGURE 2 is a semidiagrammatic top view, also somewhat in the nature of a ow sheet, showing an apparatus arrangement and positioning of some of the principal parts, involving our preferred small roll construction in an illustrative setup.

FIGURE 3 is a side elevation of the apparatus parts as shown in FIGURE 2, together with other parts, showing in more detail a preferred apparatus arrangement in accordance with the present invention.

FIGURE 4 is a semidiagrammatic side elevation View on a somewhat enlarged scale for better illustrating our small roll construction and the means associated therewith for interconnecting its operation with subsequently positioned devices and steps of the process.

Referring to FIGURE 1, the legends appearing thereon are thought to be generally indicative of the tow path through our process. It is thought sul'licient to mention with respect to this ligure that the block shown in the center of the gure about blooming and the like treatment, in its broader aspects is intended to embrace several ways of accomplishing this phase of the over-all process.

However, as will be described in detail with respect to- FIGURE 2 and subsequent figures and as already mentioned, we prefer an over-all process which not only includes our small roll pretensioning at the start of the process but includes van air jet subsequentially in the process for opening and otherwise processing the tow filaments.

Referring now to FIGURE 2 and also FIGURE 3, it will be observed that FIGURE 2 is somewhat of the same general type as FIGURE l, but is in more detail in that specic apparatus parts have been indicated and their relative location pointed out. However, here again, the legends on FIGURE 2 are thought to adequately eX- plain. Starting at the right of the figure and noting the dash-arrow line which represents the path of the tow, the tow is withdrawn from a package, bin or other source of tow supply. It passes, preferably vertically upward, through twist removal as shown by the legend which is a device in accordance with the disclosure of the abovementioned Patent 2,908,045 to one of the herein named inventors. The tow is then passed over the roll noted as first cylindrical guide. This guide, as well as the other parts, is suitably supported and positioned by one or more apparatus mounts and may be rotated by the tow. The rolls in a number of instances, as will be noted, are interconnected in a certain manner, are power driven by suitable motors; but extended discussion of such details at this point appears unnecessary.

The withdrawn tow then passes to the pre-tensioning rolls of the present invention. The pre-tensioning will be described in detail with respect to FIGURE 4.

The pre-tensioned tow is then passed through feed rolls, plasticizer applicator and jet as generally illustrated in FIGURE 2, finally reaching a roll or plug maker as will be diagrammatically noted and referred to in FIG- URE 3. The exact construction of the rod or plug maker is not a limitation on the present invention.

Referring now to FIGURE 3, it will be observed that the particular supply of tow in this FIGURE 3 is from a bale. The tow is withdrawn from this bale by means of first cylindrical guide 1. As shown in FIG- URE 3, this first cylindrical guide 1 is preferably posi- 4- tioned somewhat above the bale by using any suitable amount 2. Likewise, this mount may alsol -be adapted to hold twist removal device 3.

The tow then passes to the pre-tensioning roll assembly 21 of the present invention. As will hereinafter be observed when FIGURE 4 is considered, this pre-tensioning roll assembly is equipped with pneumatic means associated with the upper roll, which means is interconnected with the gas supply to jet 6. By such an arr-angement it is readily possible that the pressure will be relieved from the pre-tensioning rolls when the jet is not operating, thereby eliminating flat spots and unnecessary pressure on the rolls when the tow is not passing through the equipment at high speed.

After leaving the pre-tensioning rolls of the present invention, the pre-processed tow goes through feed roll assembly 4 which is positioned relatively close to the smaller pretensioning rolls. As will be noted from FIG- URE 3, these rolls 4 are substantially larger in diameter than the pre-tensioning rolls and may be of the order of 3 to l0 times larger than the pretensioning rolls. The roll assembly 4 is driven by sprocket 16. This sprocket 16, as well as the drive on several of the other parts, is interconnected by belts, chain drives or the like to obtain correlated operation. In further detail, by suitable choice of the size of the sprocket or drive on the feed rolls 4, with reference to the jet and delivery roll assembly 7, the desired speed of passage of the tow through the jet may be obtained. That is, roll assembly 7 usually is operated .at a lower speed than roll assembly 4. This permits the jet 6 to better function on the pretensioned tow. By this interconnected arrangement and the interconncetion of other parts, as will be mentioned hereinafter, the entire process may be synchronized and operated in a high speed continuous manner.

The tow from feed roll assembly 4 passes to plasticizer applicator assembly 5. The particular construction of this applicator is not a limitation on the present invention. It is suicient to indicate that suitable means should be provided so that liquid plasticizer or other treating agent may be applied to both sides of the tow before the tow enters the jet. The applicator may be conveniently mounted on supporting means 19 and 20. By this arrangement, the stand 20 may be moved to the best operating position on the tow, namely at any desired position between the feed rolls 4 and jet 6.

The tow after having been treated with plasticizer or other liquid by applicator 5 passes into jet 6 supplied with air or other fluid or gas by conduit 2S. This -gas supplying conduit 25 is equipped with a gauge as at 17 for noting the pressure and with an automatic valve 18. This valve 18 may 'be the valve which is interconnected with certain parts on the pre-tensioning rolls 21 as will be discussed with respect to FIGURE 4. The jet may be suitably held and positioned by a stand 9 comparable to stand Ztl just referred to.

We would generally use a slot jet, a jet of annular construction or construction similar to that shown in companion copending application of our co-workers Dyer and Gallagher Serial No. 856,793. However, the present invention is not restricted to a particular jet construction. It is sufficient to indicate that various suitable jets may be employed, of which a number are described in prior patents and publications.

The jet-treated tow exiting from the jet then passes into the delivery roll assembly 7 from which it passes into trumpet 8. Trumpet 8 feeds the pre-processed improved tow into a rod or plug maker. Since the rod or plug making machine is not a part of the present invention and is shown in prior patents and publications, description thereof herein is unnecessary. It is pointed out, however, certain tests and comparisons hereinafter set forth were made by processes using the present invention and -not using the present invention, 4but the Same plug maker was used in both instances for making the rods which were tested.

Referring now to FIGURE 4, there is shown in greater detail the pre-tensioning polls of the present invention. These rolls are mounted in a frame designated over-all as 31. There are several ways to construct this frame. We prefer to have a bolted-on side, as illustrated at 32, to facilitate the insertion or removal of the rolls. The upper portion of this bolted-on side, as at 33, is provided with a bearing 34. A similar type bearing would, of course, Ibe on the opposite side; hence, there is no need to discuss such features in detail since conventional bearing structures may be used. The lower roll 36 which rides in the bearings just mentioned may be constructed of a steel core with rubber covering or it may be covered with other pliable materials comparable to rubber. Or, the roll may be entirely of metal, as steel. The roll diameter is relatively small and preferably is less than 5 inches in diameter.

Positioned a-bove this roll is another roll 37 of similar size and construction. As shown, this upper roll is designed to ride on the lower roll. Likewise, this upper roll would be carried in suitable bearing means for easy rotation such as the illustrative bearing indicated at 38. This roll likewise may comprise a steel core, rubber covered or otherwise of similar construction to the lower roll. Or, it is satisfactory to have one steel roll and one rubber roll operating in combination.

However, this upper roll 37 rather than being a fixed roll as is 36 is arranged to move up and down depending on pressure applied thereto. This pressure may be applied as by conventional bellows conta-ined within housing 39. This bellows housing is mounted on a suitable plate by means of cap screws 41.

A similar construction 42 on the opposite edge of the frame is provided so as to transmit pressure to the other end of roll 37. The exact mechanical linkage and the like means used for transmitting the pressure from bellows chambers 39 and 42 to the ends of roll 37 is not a limitation on the present invention. rThe housing for bellows 39 and 42 are suitably connected to air line 43. This air line is desirably equipped with gauges and pressure reducers as indicated at 45 and 46. The air supply 43 is preferably connected into the air supply to 25 of FIGURE 3. Therefore, when the air supply is cut off to jet 6, the supply is also cut off to the bellows releasing the downward pressure on roll 37. When the process is started up again, the a-ir supplied to the jet also enters line 43 and applies pressure through the bellows mechanism to the pre-tensioning roll 37 The amount of pressure is relatively low and merely sufficient to press down on the tow so that by operating feed rolls 4 at their desired rotating speed will provide pre-tension-ing and pre-processing in the tow before the tow is fed to jet 6. Usually tension in the tow to the magnitude of -80 lbs. to cause the tow bundle to move and straighten out is satisfactory.

The construction of FIGURE 4 may 4be provided with access bolts as exemplied by bolt 48 for holding on partial side plates. This permits access to the interior of the frame to install roll 37.

While we prefer a pneumatic system such as outlined above, inasmuch as this works in conjunction with the air supply to the jet the present invention is not to be avoided by substituting mechanical, electrical or other means which may be synchronized with the starting and stopping of the jet. In brief, suitable means are provided in conjunction with one of the rolls so that the pressure of this roll against the other roll may be applied and removed in 6. correlation with the operating of the jet and, if desired, other apparatus parts subsequent in the process.

The foregoing substantially completes our description of our apparatus. However, the following is added, referring in particular to FIGURE 3 and the parts in the vicinity of reference characters 10, 11, 12, 13 and 14, for example. The various parts are belted and/or geared together so that a single motor may drive many of the parts at the desired speed and sequence. When the plasticizer applicator 5 is operating, the drive train indicated by 10-11-26-14-12-15 operates pumps to deliver the required amount of the liquid thereto. The particular way of correlating the operation of the various parts is not a restriction on the present invention 'but the feature of suitable correlated action between the parts is a part of the present invention.

While from the above detailed description of apparatus construction it is thought already apparent how our process may be operated, further information will be had from a consideration of the following brief example which is set forth for illustrating the preferred embodiment of our invention.

Example In accordance with this example, Ithe tow employed was commercially available continuous filament crimped acetate tow. As is known, this tow is in a relatively highly crimped state of 10 to 20 crimps per inch. Hence, the feed product Was somewhat non-uniform in length per unit weight and vice versa. This compacted tow was withdrawn from the package in which it was received at the factory. It was then passed through our preferred form of apparatus as illustrated in detail in FIGURE 3. The tow in this particular example was run through Ithe twist removing device 3 as shown in detail in said Stevens Patent 2,908,045, already referred to above. The tow was then subjected to the pre-processing of the present invention by means of the small rolls as illustrated in detail in FIGURE 4 and shown at 21 in FIGURE 3.

The pre-processed tow was then `conducted through the larger feed rolls 4 of FIGURE 3, through the plasticizer applicator 5, and through the jet and other parts and devices shown in FIGURE 3 into the plug maker to obtain rods or plugs for test.

The particular plasticizer applied in applicator 5 in this example was material known as glycerol triacetate. However, other plasticizers compatible with the filaments could be used. For the purposes of the comparisons of the present example, as long as the same plasticizer is used in both runs to eliminate introducing a variable, the comparative results would be unaffected.

Likewise, the air pressure utilized in jet 6 and on the bellows of -thepre-tensioning rolls was the same. In other words, in this particular example a certain amount of tow was run through the process utilizing the pretensioning rolls of the present invention. Then, further tow from a suitable source and of a suitable denier to give rods of same pressure drop was run through the same process `and apparatus with conditions as comparable as possible excepting that the pre-tensioning rolls and the pre-processing of the present invention were not used. Hence, both groups of rods produced were in general the same and any differences could be attributed to the pretensioning process and apparatus of the present invention.

The resultant two groups of rods or plugs were visually examined and tested for uniformity and deviation by the same test procedures. The illustrative results are tabulated below.

From this comparative table it will be observed that the order of weight of both rods were about the same and yield the lighter weight type rod having a weight below .8 gram. Being able to secure this lower weight indicated that the rods were requiring less material and otherwise represented some savings over prior art rods, which in many instances have weighed .82 gram or heavier per rod.

The 4circumferences of both rods were held constant at 24.6 rnm. and the over-all general size of the rods was not noticeably changed and was such that the rods were readily utilizable for cigarette lter purposes. Likewise, the pressure drop through the rods was approximately the same. Hence, it is apparent that the application of the present invention to cigarette lter rod manufacture, while improving certain features did not at the same time materially or adversely affect other properties or features of the product. However, it will be observed under the headings of the `above table of Std. Dev., meaning standard deviation, that the uniformity of the rods in the foregoing areas had been noticeably improved. For example, where a weight variation without using the present invention gave a numerical statistical value of .0215, this was reduced by the present invention. Using the prerent invention, this deviation was reduced usually of the order of greater than 50% to the value of .008. The exact manner of testing the improved rods of the present invention and the exact numerical values obtained in such test methods is not a limitation on the present invention. There are several publications which discuss such deviation measurements. Davies-Statistical Methods in Research and Production, 3rd edition- Hafner Publishing Company, New York City, 1958, is mentioned as illustrating such a publication.

In our tests on this weight deviation item, 1,000 separate rods produced by each method were separately weighed. Any deviation and the frequency of deviation from the normal were noted and the above deviation values calculated. In other instances, such as pressure drop, the tests were based on a comparison of 25 rods produced by one method compared with 25 rods by the other method. Although testing a larger number of units in some instances may be desirable, the tests referred to herein on a smaller group of units indicated clearly that uniformity had been improved. Hence, extended testing to merely measure the extent of such improvement seemed unnecessary. In a number of instances the rods produced by the present invention when the purchaser or user of the rods had occasion to employ them for his purposes were found by him to work better in his equipment. Hence, the improvement of the rods was such as to be readily noted by a consumer.

Utilization of other pre-tensioning devices in the process of the present invention such as the tension gate referred to above is regarded not as efficient and easy on the Itow as the preferred roll construction described in detail above. Nevertheless, such other pre-tensioning devices have some merit. As apparent to a substantial extent from FIGURE 4, the pneumatic arrangement associated with our small roll device is advantageous as follows. If the process is stopped and the rapid passage of the tow therethrough stopped, our pneumatic arrangement automatically functions to relieve roll pressure on the tow. This not only eliminates possibility of filament flattening or damage but prevents flat spots developing on the rolls which might later contribute to non-uniformity. lnasmuch as the apparatus herein described operates at speeds of rod production of the order of 1,000 rods per minute or greater, it is thought that it will be readily apparent why it is desirable to have the referred to automatic interconnection and correlation to be able to immediately remove the tension and pressure from the tow when the process is stopped for any purpose. It is further explained, that although the pretensioning and the jet may be interconnected to the same gas supply this does not mean the same gas pressure is used on each unit. The size of the bellows 39 and the like factors determine the desired pressure thereon and operating factors determine jet pressure. Hence, usual regulating valves are included in the lines to each device.

The particular tow used in the present process and apparatus was, `as mentioned, crimped cellulose acetate tow. We prefer to use continuous multifilament crimped tow such as described in the several Crawford and Stevens patents, 2,794,239, 2,953,837 and 2,953,838. However, other high quality tows may be processed in a comparable manner in the apparatus above described with improved results. Likewise, various kinds of plasticizers or other treating liquids or the like may be used as well as various conditions of pressure on the jet and the like operating conditions.

ln the above disclosure Ithe matter of improvement in weight deviation as respects rods of under .8 gram and of substantially the same circumference, shape and size has been indicated as a comparison between .008 and .02. Such values may also be expressed in terms of a coefcient of variation of not greater than about 1%. Such coefficient may be a more convenien-t reference in making a comparison between rods of different shapes and sizes.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the -invention as described hereinabove, and as defined in the appended claims.

We claim:

1. An apparatus for producing an opened tow having a substantially uniform weight per unit length comprising in order from the direction of the feed:

(a) a pair of relatively small tow pretensioning rolls adapted for braking, arranged so that the tow is pulled through the bite formed between said rolls,

the braking action of said relatively small rolls being sensitive to changes Vin the length and weight of tow delivered to said apparatus,

(b) constant linear speed tow feed rolls, and

(c) pneumatic tow-opening means.

2. The apparatus of claim 1 wherein the apparatus is further characterized by automatic means for releasing the pretensioning rolls when the pneumatic opening means are inoperative,

3. In apparatus for roll treatment of continuous lament tow, the improvement which comprises a pair of pretensioning rolls `adapted to turn countercurrently while applying a pretension to tow passing through a nip formed therebetween and a pair of mechanically driven feed rolls in juxtaposition with said pretensioning rolls, said feed rolls being of the order of 3 to 10 times larger than said pretensioning rolls and adapted to conduct tow passed through the nip formed between said pretensioning rolls to further treatment means, said pair of pretensioning rolls being operatively connected to and equipped with pneumatic means associated with one of ysaid rolls, said pneumatic means being interconnected with gas supply to a jet for opening tow positioned for passage of tow therethrough after being conducted through the nip formed between the feed rolls, and said pneumatic means being responsive to changes in air supply to said jet whereby pressure may be relieved from the pretensioning rolls when said jet is not operating, thereby minimizing at spots and excessive pressure on said pretensioning rolls.

4. The improvement of claim 3 wherein the pretensioning rolls are mounted in a frame having a bolted-on side in association with a spring or weight loading one roll against the other whereby the insertion and removal of the rolls is facilitated.

(References on following page) References Cited bythe Examiner UNITED STATES PATENTS Crawford et a1. 156-441 Jackson 131-208 Schur et a1 131-208 Crawford et al. 156-61 Mahoney et al 19-66 X MELVIN D. REIN, EARL M. BERGERT, Examiners.

DONALD W. PARKER, Primary Examiner.

P. R. WYLIE, L. K. RIMRODT, Assistant Examiners. 

1. AN APPARATUS FOR PRODUCING AN OPENED TOW HAVING A SUBSTANTIALLY UNIFORM WEIGHT PER UNIT LENGTH COMPRISING IN ORDER FROM THE DIRECTION OF THE FEED: (A) A PAIR OF RELATIVELY SMALL TOW PRETENSIONING ROLLS ADAPTED FOR BRAKING, ARRANGED SO THAT THE TOW IS PULLED THROUGH THE BITE FORMED BETWEEN SAID ROLLS, THE BRAKING ACTION OF SAID RELATIVELY SMALL ROLLS BEING SENSITIVE TO CHANGES IN THE LENGTH AND WEIGHT OF TOW DELIVERED TO SAID APPARATUS, (B) CONSTANT LINEAR SPEED TOW FEED ROLLS, AND (C) PNEUMATIC TOW-OPENING MEANS. 